As a method of manufacturing a medical needle that has a hollow metallic needle body on which a needle tip that can be punctured into a living body is formed, and a resin needle hub which is fixed to a proximal portion of this needle body, there are known a bonding method and an insert molding method. With the bonding method, a needle body and a needle hub are manufactured separately, and the needle body and the needle hub are fixed to each other using an adhesive. On the other hand, with the insert molding method, a needle body is set into an injection molding mold for molding a needle hub and a resin is injected into the injection molding mold, thereby molding the needle hub integrally in a proximal portion of the needle body.
JP-A S62-243564 proposes a method of manufacturing a medical needle by the insert molding method. Specifically, with the manufacturing method of JP-A S62-243564, a core pin is inserted into a needle body from a rear end portion of the needle body, thereby forcibly widening the rear end portion into a flare shape, and a resin is then injected into an injection molding mold, thereby molding a needle hub.
The manufacturing method of JP-A S62-243564 can have a problem that when the core pin is pulled out from a molded article after the injection molding, the needle body proximal portion (flare-shaped portion) returns to an original state by spring back, resulting in the generation of a level difference and burrs/flashes in a boundary section between the needle hub and the needle body in an inner peripheral portion of the needle hub. In particular, when a medical elongated body (for example, a guide wire) is inserted into a medical needle from a proximal side of the medical needle and the level difference and burrs/flashes described above are present, it can be difficult to smoothly insert the medical elongated body.